2004 Chevy Cavalier compressor cycling

BOBCAREY

MEMBER
2004 CHEVROLET CAVALIER
4 CYL
FWD
AUTOMATIC
50,000 MILES

AC Compressor is cycling on I believe the high pressure switch when idling. Compressor runs fine when car is moving and air is forced thru condenser coil. Should the radiator cooling fan be running the entire time the ac in on. If not what energizes the fan when ac is on. Also at what pressure does the high pressure and low pressure switches open and close.
Thanks for your help.
Bob

1 Reply

ZACKMAN

MECHANIC
4,202 POSTS

AC Compressor is cycling on I believe the high pressure switch when idling. Compressor runs fine when car is moving and air is forced thru condenser coil.

Should the radiator cooling fan be running the entire time the ac in on.
***Yes***

If not what energizes the fan when ac is on.
***The cooling fan has two speeds. Low speed is controlled by the engine coolant temperature sensor by sending a signal to the PCM. High speed is controlled by the AC refrigerant pressure switch sending the 5V reference to the PCM. High speed fan is continuously ON for as long as the AC is ON.***

Also at what pressure does the high pressure and low pressure switches open and close.
***PCM compares the AC system pressure to the ambient air pressure. They have to be within 15 psi. PCM also relies on 5 volts reference coming from the pressure switch. Without the AC running, the PCM "sees" less than 4.5 volts.***